Update NewestKubernetesVersion to v1.17.0-beta.1

Use faster build for the default minikube target

Adding priyawadhwa as minikube approver

small travis test changes

Add instructions for including supporting documents with MEP proposal

Remove heapster addon

Silence virtualbox registry check

Store kubernetes clientset when waiting for apiserver

update releases.json to include v1.5.2

fix cron script installation

Fix spelling of HTML for golint on bindata

Reportcard again, golint and gocyclo.

Since the docker image is always running Linux amd64, we need to
pass the actual local target to build (cross-compile) minikube for.

When not rebuilding everything all the time, we need to check
the go.mod for changes to the list of dependencies (and rebuild).

When we are doing the "cross" compile targets, we
force rebuilding all packages (up-to-date or not).

For the default native target "out/minikube", we
can do a much faster build (10x!), for development.

Leaving all the cross target to rebuild, as before.

Also the _test.go files are only used for unit tests.

Supposed to be removed in 361222f6, along with
some other random changes to comments and such.

update examples to use "kubectl create"

While looking at pprof data, I noticed that the line:

```go
client, err = k.client(k8s)
```

takes around .9 seconds to complete. Previously, we were calling it on
every iteration of the waitFor loop. Instead, if we store the clienset once
we have it, we should be able to speed up this function.

During local testing, this optimization reduced time spent waiting for
the apiserver by 13 seconds on average.

Disable brew cask updater

Version bump to v1.5.2